Video camera

Whole-cell voltage clamp recordings were made from cones. The recording chamber containing the isolated retina was mounted on a Nikon Eclipse E2000FN microscope (Nikon, Japan) and viewed with a Nikon 60× water immersion objective with infrared differential interference contrast and a video camera (Philips, Netherlands). Recording electrodes were pulled from borosilicate glass (BF-150-110-10; Sutter Instruments, Novato, CA, USA) with a Flaming/Brown micropipette puller (Model P-1000; Sutter Instruments, Novato, CA, USA). The impedances ranged from 8 MΩ to 12 MΩ when filled with pipette medium and measured in bathing solution. Pipettes were connected to an Axopatch 200A patch clamp amplifier (Molecular Devices, Sunnyvale, CA; four-pole low-pass Bessel filter setting, 2 kHz). Signal software (v. 3.07; Cambridge Electronic Design (CED), Cambridge, UK) was used to generate voltage command outputs and to acquire data. Signal software (v. 3.07; CED), MatLab (v2016b, MathWorks), Igor.pro (WaveMetrics, Portland, OR, USA) and Origin Pro (v8, Origin Lab Corporation), were used to analyze the data. All data shown are corrected for the junction potential.

Whole-cell voltage-clamp recordings were performed from GFP-labeled GCs in retinas mounted (GC side up) in a recording chamber (Warner Instruments, Hamden, CT, USA). The recording chamber was mounted on a Nikon Eclipse E2000FN microscope (Nikon, Tokyo, Japan) and viewed with a Nikon 60x water immersion objective with infrared differential interference contrast and a video camera (Philips, Eindhoven, the Netherlands). The GFP-labeled cells were identified using a short flash of 450–490 nm light.